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Thread: Tesla fire (trying again)

              
   
   
  1. #11
    Empulse R #24 frodus's Avatar
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    You actually want to use water on a lithium pack if possible. Sure it'll short things... But you're trying too cool the batteries. Most fires I've seen are due to thermal runaway and the best way to stop that is to cool them back down. Its what Motoczysz did at PIR when their pack overheated. Probably saved the motorcycle from being a total loss.
    Travis

  2. #12
    teddillard
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    I was at a conference on Monday - the Alt Wheels Fleet Day, and they were talking about the EV plate that's available in Massachusetts now. Part of it is to support EVs of course, but the other part is to alert First Responders to the fact that it's an EV.

  3. #13
    Seņor Member podolefsky's Avatar
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    The post by Musk said: When the fire department arrived, they observed standard procedure, which was to gain access to the source of the fire by puncturing holes in the top of the battery's protective metal plate and applying water. For the Model S lithium-ion battery, it was correct to apply water (vs. dry chemical extinguisher), but not to puncture the metal firewall, as the newly created holes allowed the flames to then vent upwards into the front trunk section of the Model S. Nonetheless, a combination of water followed by dry chemical extinguisher quickly brought the fire to an end.
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  4. #14
    SMPS Engineer BaldBruce's Avatar
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    Just wanted to point out the obvious. Not all Lithium chemistries are equal. Tesla chose high energy and high power (LCo and NCA) and thus they can and do catch fire if mutilated. This is not true of other Li chemistrries. Most of us are using LFP which trades off energy density for better safety and longer life. All batteries can release enough energy to start a fire and are themselves fuel. Some are just more volitale than others.

    Link to the battery university summary done a little while ago on Li types: http://batteryuniversity.com/learn/a...on_chemistries

    Tesla is way safer than all gasoline vehicles IMO and the data over time will eventually prove it, even with their choice of higher energy density Li chemistries.
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  5. #15
    Seņor Member podolefsky's Avatar
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    Very good points, Bruce. That Battery U page is definitely worth reading - and noting which EVs are using which chemistry - AFAIK most recent production elmotos are using NMC. I believe RC lipo is essentially an LCo pouch cell?
    - Noah Podolefsky -
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  6. #16
    Junior Member Toni's Avatar
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    What is worth noting is that LiFePo4 chemistry that most of us seem to use, should be inherently safer than the cobolt & manganese based cells used in Teslas. A way safer for home conversions I'd think. Even in the event of puncture you'll most likely end up with smoke, but not fire.

    PS. I had my battery cases built from 4mm aluminum sheet. Should protect them in the event of tipping over etc. minor mishaps...

    PPS. Oh just noticed Bruce also pointed out the chemistry difference. (Didn't realize there was 2 pages of comments.)
    Last edited by Toni; 10 October 2013 at 0116.
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  7. #17
    teddillard
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    Here's the video of the fire.



    Pretty much validates what Tesla said about the fire not making it into the passenger compartment.

    Here are a few videos of mostly Luke trying to make a fire:











    Finally here's a warehouse fire simulation:



    Here's my own attempt at making a lipo fire video:



    After posting that I got a whole bunch of helpful comments about the fairly specific conditions I needed to make a proper lipo explosion. I even tried a few.

    Non-issue IMO. My batteries, whether RC lipo or CALB or Headways are hanging right out there in the breeze, and will stay that way, because I don't see any reasonable argument that it's any more dangerous than this:



    My personal favorite:



    I'm fairly certain all of these have been posted here before, under the Battery category (which this thread should be under, IMO).

    I'd love to find the video of the TTXGP battery fire that was Muench, I believe, but if memory serves it was just kind of a smoldering event. I've seen more brushes catching fire than battery fires on the racing sites.

    Battery fires will give you hours of pleasure on YouTube, but it's not something I even discuss with people who are asking about the bike. If they're not satisfied with the statement that they're safer than gasoline, I just ignore them. I may explain about RC and laptop batteries and the dangers of those, if they appear to be listening, but I strongly feel that the more traction you give to this discussion the more you're contributing to the mis-information noise. I ignore it, because anyone outside the community who's latched on to this as a talking point against EVs doesn't want to hear the facts anyway.

    Quote Originally Posted by podolefsky View Post
    Maybe everyone knows this - seems to me, it doesn't get discussed much. Or worse, gets dismissed. The Tesla example is instructional - why did it happen? What kind of cells were they? How can we learn from it to make our bikes safer?
    Sorry, but first, it seems to me like it's discussed constantly. Every time RC lipo gets brought up it's ressurrected. Second, yes, I feel out of all the safety issues in building and riding a motorcycle, it should be pretty much dismissed outside of the obvious "you're dealing with 80+ volts and 500 + amps" which is HUGELY more important to understand than what happens if they get punctured in some freak accident. (By the way, that would be my concern with using a material like 4mm aluminum sheet for your battery box, but that's been discussed here to death as well. I'm far more concerned about that shorting out in a crash than any punctures without it.) Finally, I don't see what I can learn about building my pack if this car - this car, mind you, got hit by a huge spike that went through 1/4 in steel.

    What I take away from this is simple. Don't get hit by low-altitude missiles.
    Last edited by teddillard; 10 October 2013 at 0448.

  8. #18
    Seņor Member podolefsky's Avatar
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    Here's how much of a non-issue it is:







    In the last one, they weren't balance charging. It's not uncommon for people to bulk charge large lipo packs and only balance charge on occasion.
    - Noah Podolefsky -
    The GSX-E

  9. #19
    Seņor Member podolefsky's Avatar
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    ..
    Last edited by podolefsky; 11 October 2013 at 1409.
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  10. #20
    teddillard
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    Oh, right, OK. I thought this was about **** puncturing your packs in a laydown or accident, like the Tesla in the OP. My mistake.

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